Adding Fractions with Unlike Denominators

Adding Fractions with Unlike Denominators

I can add fractions with unlike denominators.

• 
  

Example,  Add:

          $\frac{1}{2}\ +\ \frac{1}{4}$  

We can not add the fractions the way they are now. We must have the same size pieces.

We have different size pieces, we need the same size pieces to be able to add!

Open Ended

What could we do to be able to add these two fractions together?

 $\frac{1}{2}\ +\ \frac{1}{4}=$  

All we need to do is cut the pieces!

We will take the $\frac{1}{2}$  and turn it into 4ths

Poll

By cutting the

 $\frac{1}{2}$  in half, did we change the value of it?

• Yes

• No

No, we did not change the value!

 $\frac{1}{2}$  is the same as  $\frac{2}{4}$   

        $\frac{1}{2}\ =\ \frac{2}{4}$  

We don't alway have to cut the pieces. Instead, we can use math to find the Least Common Multiple.

Multiple Choice

List the multiples of 2 and 4. Choose the LEAST common multiple.

• 2

• 3

• 4

• 8

Open Ended

So, what is the answer to 1/2 + 1/4?

Example 2:

Add

 $\frac{1}{3}\ +\ \frac{1}{4}$ 

 

Multiple Choice

List the multiples of 3 and 4. Find the LEAST common multiple.

• 3

• 4

• 8

• 12

Poll

What is 1/3 + 1/4?

• $\frac{2}{7}$

• $\frac{7}{12}$

• $\frac{7}{13}$

• $\frac{7}{24}$

Example 3: $\frac{2}{5}+\frac{3}{10}=$  

1. Are the denominators equal?
2. No, so list the multiples of the denominators
3. Multiply your fractions to create a common denominator
4. Add the numerators once the denominators are equal.

Open Ended

2/5 + 3/10

Poll

 $\frac{3}{4}\ +\ \frac{1}{6}\ =$  

•  $\frac{4}{10}$  

•  $\frac{1}{2}$  

•  $\frac{11}{12}$  

•  $\frac{22}{24}$  

So the answer is:

 $\frac{3}{4}+\frac{1}{6}=\ \frac{11}{12}$  

Practice Work

https://quizizz.com/join?gc=37395472